SAN DIEGO — A team of researchers led by the University of California, San Diego’s Scripps Institution of Oceanography has discovered a new species of fish that lives in the eastern Pacific Ocean off Costa Rica.

What You Need To Know

  • Pyrolycus jaco is a newly identified species of eelpout living in a hydrothermal seep in the deep ocean

  • It is the first fish species to be described from the hydrothermal seep site known as Jacó Scar, located on the Pacific margin of Costa Rica

  • It is a member of the eelpout family, measuring roughly 6 inches long with a light pink to lavender colored body

  • The name comes from their distinctive eel-shaped bodies, and in some species, what appears to be a “pouting” expression of the mouth

When Dr. Charlotte Seid looks at video taken deep in the sea, she sees interconnected beauty.

“Once you know what to look for, those adorable beady eyes are everywhere,” she said, pointing out the little pink fish. It is a newly identified species of eelpout that was found more than a mile below the surface of Costa Rica.

A team of researchers led by UC San Diego’s Scripps Institution of Oceanography captured a video, but they didn’t recognize it as a new species at the time.

“If you look at just one frame of any video in the deep sea, there’s probably lifetimes of work to be done,” Seid said.  

When Seid examined a specimen that was brought back to San Diego, she couldn’t quite place it. She enlisted the help of Ben Frable, who manages the Marine Vertebrate Collection at Scripps.

“We have about 2 million fish specimens, about 140,000 jars, representing over 6,000 different species of fish!” Frable said.  

Together, they worked with other experts to generate a 3D digital X-ray to examine the skeleton without damaging the specimen. They confirmed it was a new species and named the mystery fish Pyrolycus jaco after the area where it lives.

Frable is excited to add this new species to their collection where it will help scientists continue to study the deep sea.

“It’s very satisfying. Starting out as a student, I had just had this conception that all the species had been found or we had kind of discovered at least all the fish on the planet,” Frable said. “And that’s really not true. There’s actually 300-to-500 new species of fish being described by scientists around the world every year.”

They believe there are still many more discoveries to be made, and it shows just how important it is to explore and protect deep-sea habitats.

“I hope more than anything that people are inspired to look very closely at every spot on earth, especially the deep sea; to appreciate the marine biodiversity that lives in there; but also the scope of work, effort and, dare I say, love that scientists put in,” Seid said.  

Several grants from the National Science Foundation and Schmidt Ocean Institute funded the work.